Detection of microorganisms in body fluids, water and alimentary products allows diagnostic and prognostic of many infectious diseases. Cells and microorganisms needed for the making of vaccines demands a severe control of the sterility of the produced media, usually achieved by culturing an aliquot of the medium whose sterility one wants to control, in a growth-promoting medium during several days. Said growth and identification of microorganisms are time consuming, difficult and frequently takes two to three weeks before results are available.
For diagnostic purposes, such a method of determination relying on culture of blood sample or of sputum exists, when there is a need to diagnose the presence of mycobacterial entities. The time needed to arrive at a diagnostic conclusion is however very long, extending sometimes to 4 weeks. For other microorganisms, such as the etiological agents of malaria (especially Plasmodium falciparum, leishmaniasis, gonorrhea, syphilis, tuberculosis, malaria, tick-borne Lyme disease, as well as meningitis due to a variety of vectors such as Neisseria, Haemophilus, Streptococcus, Listeria and Mycobacterium, a rapid diagnostic method putting the whole pathogen in evidence does not exist and there is a need for such rapid method.
Rapid methods of detection of antigens and antibodies are now currently in use for antibodies and proteinic and glycoproteinic antigens whose size is sufficiently small for them to be transported in a lateral flow chromatographic system. For larger entities (such as whole bacteria and eukaryotic organisms), this technique is inapplicable because the analytes are too big to move with the flow. These microorganisms of large size are also able to condense on retaining membranes in such a way that the sensitivity of their detection in situ is considerably enhanced.
However, an intolerably high level of false positive or negative results is also observed. The phenomenon of immunological quenching induced by body fluids is well known. This quenching prevents the recognition of the whole organisms by specific binding partners as antibodies and induces false negative results.